8 research outputs found
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Material end-plugging for the Scylla IV-P linear theta pinch
Scylla IV-P is a 5-m linear theta pinch at the Los Alamos Scientific Laboratory primarily used to study end effects of linear theta-pinch plasmas. One method that may be used to reduce plasma end loss from linear theta pinches is to insert material end plugs. Two different assemblies that insert end plugs have been fabricated and installed on Scylla IV-P. The presence of the material end plugs have been found to increase the plasma confinement time by 20 to 30 percent; the plasma stability is increased (the m = 1 wobble is suppressed), and the neutron production is not degraded. The design of the end plug insertion mechanisms is described in some detail and information is presented on end plug erosion. Material eroded from the end plug must be either removed by the vacuum system or it plates out on the vacuum system surfaces. A condensed gas end plug has been proposed to eliminate problems associated with ablated solid material; a third end plug assembly for this is being designed which inserts a cryostat coated with a condensed gas. A prototype of this cryogenically cooled end plug (cryo-plug) has been fabricated and tested. These data are presented and the insertion mechanism described
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Development of a 130-mA, 75-kV high voltage column for high-intensity dc proton injectors
A reliable high-voltage (HV) column has been developed for dc proton injectors with applications to high-intensity cw linacs. The HV column is coupled with a microwave-driven plasma generator to produce a 75-keV, 110-mA dc proton beam. Typical proton fraction from this source is 85--90%, requiring the HV column and accelerating electrodes to operate with a 130-mA hydrogen-ion beam current. A glow-discharge, which was caused by the ion source axial magnetic field, was initially observed in the HV column. This problem was solved by scaling the electron production processes, the magnetic field, and the HV column pressure into a favorable regime. A subsequent 168 hour reliability run on the 75-keV injector showed that the ion source (plasma generator and HV column) has >98% beam availability
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Mechanical engineering of a 75-keV proton injector for the Low Energy Demonstration Accelerator
A dc injector capable of 75-keV, 110-mA proton beam operation is under development for the Low Energy Demonstration Accelerator (LEDA) project at Los Alamos. The injector uses a dc microwave proton source which has demonstrated 98% beam availability while operating at design parameters. A high-voltage isolation transformer is avoided by locating all ion source power supplies and controls at ground potential. The low-energy beam transport system (LEBT) uses two solenoid focusing and two steering magnets for beam matching and centroid control at the RFQ matchpoint. This paper will discuss proton source microwave window design, H{sub 2} gas flow control, vacuum considerations, LEBT design, and an iris for beam current control
Developmental changes of the hand skeleton induced by grafting leg mesoderm to the wing bud in the chicken
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Comparison of Simulations with Measurements for the LEDA LEBT H
The Low-Energy Demonstration Accelerator (LEDA) injector is designed to provide 75-keV, 110-mA, proton beams for the LEDA RFQ. After testing the LEDA injector using a 1.25-MeV, CW RFQ, the authors shortened the low-energy beam transport (LEBT) to 2.69 m, replaced the first LEBT solenoid with one that has a shorter length but the same focusing power, and installed and operated the LEDA injector in the beam tunnel. In this paper the authors use the TRACE, SCHAR, and PARMELA computer codes to model the proton beam for the as-installed LEBT and the authors compare the results of these simulations with the LEBT beam measurements. They use the computer code PARMTEQM to transport the SCHAR- and PARMELA-generated beams through the RFQ so that they can compare the predicted RFQ performance with the measured RFQ performance. For a 100-mA, 0.239-{rho}-mm-mrad input beam, PARMTEQM predicts the LEDA RFQ transmission will be 92.2%